Current distributing means for electrolytic processes



May 18, 1943 R. C. OLSEN CURRENT DISTRIBUTING MEANS FOR ELECTROLYTICPROCESSES Filed Dec. 24; 1940 Snnentor 0135723 6 @Zwzz/ Patented May 18,1943 UNITED STATES PATENT OFFICE CURRENT DISTRIBUTING MEANS FORELECTROLYTIC PROCESSES Robert C. Olsen, Detroit,- Mich., assignor toTernstedt Manufacturing Company, Detroit, Mich., a corporation ofMichigan Application December 24, 1940, Serial No. 371,486

1 Claim. (01. 204-228) g r electrolyte but may-include, particularly inthe Considerable diificulty is encountered in electrolytic processes inobtaining the desired distribution of current over the surfaces of theelectrodes. This is particularly true in processes which requirerelatively narrow limits of the current densities at the electrodesurfaces in order to effect the desired results. In chromium plating,for example, .or in bright nickel plating, fairly accurate control ofcurrent densities is necessary to maintain satisfactory brightness ofthe deposits. at the surfaces, as, for example, the quantity orthickness of electrodeposits, is also dependent upon the current densityover the areas involved and uniformity of actions is obtainable .only baccurate control of current distribution.

It is recognized that the difiiculty in question is due to varyingresistances offered to the flow of The extent of electrolytic actioncurrent. discharging or redistributing portion, materials adapted tosupply coatings for the cathode or work. In electroplating operations,for example, the current distributing part may be of the metal beingdeposited such as nickel, or.

example, to modify the form of the anode to make it conform more closelyto the contour of the cathode or work. Cathodic appendages, commonlytermed robbers, are also frequently employed to shield portions of thecathode that are nearer the anode. The latter devices are of onlylimited utility since they merely divert current entirely unconnectedelectrically except through.

the electrolyte with either ofthe electrodes. This means may however, asa matter of convenience,

particularly where oneelectrode, as the cathode or work, travels throughthe electrolyte, be supported upon the electrode by suitable insulatingmeans, Its mechanical features may be widely varied but compriseessentially a current collecting part positioned in the electrolyte inthe path of current flow and a current distributing part,

.said parts so proportioned and positioned with reference to the anodeand cathode as to collect,

direct, and/or redistribute the current in accordance with the desiredapportioning of current densities.

the process. It should ordinarily be inert in the The material of thedevice will vary, of course, with the nature of the electrolyte and IWhere the metal being deposited is supplied by the electrolyte, as inthe usual chromic acid chromium plating baths, such part may be of .any

suitably inert metal, as lead, lead-coated copper,

or soft steel.

It will be understood that, if plating metal is being supplied in partby the current distributing means, such metal must be replenished atintervals. It is therefore convenient, in such cases, to provide meansfor removal or replacing of the current distributing portion. Thecurrent collecting portion, however, is of indefinite life sinceelectrolytic action at its surface tends to deposit metal rather thanremove it.

In the accompanying drawing Figure 1 is a diagrammatic view illustratingthe application of the invention.

, Figure 2 is a view more in detail, showing the form of the currentdistribution modifying device as designed for a particular use.

Figure 3 is a cross section on line 3-3 of Figure l. v

, In the drawing, 5indicates a suitable receptacle, hereinafter referredto as a tank, shown in cross-section and which may be of any size andlength depending upon the character and extent of theelectrolyticprocess.

The electrolyte is marked 1. Over the tank are positive and negative busbars 9 and II and currentis supplied by a generator G. The anode I3 issupported as at IS on the positive bus bar and th cathode li-the work-issupported on the negative bus bar by means such as a hook 19. In theembodiment shown the work is a part of a motor vehicle grille. .It isirregular in shape and as explained above the work would receive acoating of unequal thickness were no provision made to correct such adefect. r

The difllculty is overcome by the use of a redistributing means in theform of an intermediate anode markedll shaped to conformto the outlineof the work as shown by Figure 1.

- In practice the work travels through the electrolyte and it isdesirable to support the anode 2| "from the work itself so that it moveswith the work and the space relation between the intermediate anode andthe work remains unchanged. The anode 2i may. be of nickel wire in theprocess ofplating a surface with nickel.

marked 21 and 29.

In order to gather more current ther is assoiciated with theintermediate anode a collector plate marked 23. The ends of the nickelwire 2| are secured to the collector plate as shown at To support theassembly of parts 2land 23 there are used insulating members of BakeliteMember 21 carries a hook 3| which engages in an opening in the lower endof the work. Member 29 carries an undercut attaching element 33 forengaging an upper part the work travels through the electrolyte.

While the invention has been described herein as applied specifically tothe electroplating art for which it was more particularly designed, itwill be understood that, in its broader aspect, it is applicable toother fields in which it becomes desirable to modify the distribution ofelectric current over the surfaces of electrodes employed inelectrolytic processes. v

I claim:

The combination with 'a tank, an electroplating electrolyte therein.anodes fixedly supported in said electrolyte, work-supporting meansarranged to travel through said electrolyte past said anodes and tosupport irregularly shaped work, and means to cause electric current toflow through said electrolyte between said anodes and said work, of acurrent-collecting and distributing device spaced from said anodes andunconnected therewith but positioned in the pathof said current, saiddevice having a current-collecting part composed of metal other than theplating metal positioned nearer the anodes than the work and arcurrent-distributing part composed of plating metal positioned nearerthe work and conforming in contour to the contour of irregularities ofthe work throughout substantially the entire area of the irregularities,and means for insulatingly supporting said device fixedly upon the workso as to travel therewith.

ROBERT C. OLSEN.

